<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .dashed{
            height: 1px;
            background: linear-gradient(to right, #000, #000 2px, transparent 2px, transparent);
            background-size: 4px 100%;
        }
    </style>
</head>
<body>
    <!--自定义虚线-->
    <div class="dashed"></div>
</body>
</html>